On Thursday, April 26, 2001, at 05:00 PM, Vladimir Shapovalov wrote:
> I have tried the two VNC viewers for Mac OS X posted on the apple
> software download site (not counting VNCThing which is not available
> anymore), and both run waaay slower than the old classic viewers. Even
> VNCDimension being written in Cocoa is annoyingly slow (on a G3 336MHz
> with 128MB RAM, OS X 10.0.1). Does anyone know what the deal is, and
> whether we should expect faster clients?
Yeah, the deal is that I'm using a Cocoa object called NSBitmapImageRep.
It's pretty fast on an OPENSTEP x86 machine, even one with less than
1/5th the horsepower of my G4's. However, it stores bitmaps in RGBA
format. Macs apparently use a reverse of that format. So every pixel has
to be translated by the graphics system. That's a big part of the slow
down - I profiled my app and 80% of the time is spent in the operating
system's graphics layer, presumably massaging that data. It's not as big
of a hit on G4's since the graphics system can use some Altivec muscle
on it, but it would be even better of that doesn't have to happen. I'm
in a middle of a re-write and part of that is to drop down to the
CoreGraphics level. Some of this is still in flux (on Apple's part), and
when VNCDimension was originally written, the CoreGraphics level really
wasn't ready for Cocoa apps to directly access.
I hope to have a new rev out in a 2 weeks or so. In the meantime, I'm
open to suggestions as to what to place as a higher priority. Here is
what's slated for the next rev:
* dropping down to CoreGraphics
* preferences panel
* KeyChain support for password storage
* re-write of the threading and SMP support - right now, simultaneous
VNC sessions are in separate threads for decoding, but sending is all
from the main thread
Things that may make it for above rev or may slip a bit:
* tight encoding
* zlib support
* ssh tunnel integration
..Bill Chin
M Dimenson Technology
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